Frontiers in Microbiology (Apr 2019)

Antimicrobial Activity of Lactobacillus Species Against Carbapenem-Resistant Enterobacteriaceae

  • Chi-Chung Chen,
  • Chi-Chung Chen,
  • Chih-Cheng Lai,
  • Hui-Ling Huang,
  • Wen-Yu Huang,
  • Han-Siong Toh,
  • Tzu-Chieh Weng,
  • Yin-Ching Chuang,
  • Yin-Ching Chuang,
  • Ying-Chen Lu,
  • Hung-Jen Tang,
  • Hung-Jen Tang

DOI
https://doi.org/10.3389/fmicb.2019.00789
Journal volume & issue
Vol. 10

Abstract

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ObjectiveThis study aims to identify suitable lactobacilli that have anti-carbapenem-resistant Enterobacteriaceae (CRE) activity with in vitro tolerance to pepsin and bile salts.MethodsFifty-seven Lactobacillus spp. strains encompassing nine species were collected for investigation. Their viabilities in the presence of pepsin and bile salts were tested using tolerance tests. Their anti-CRE effects were assessed by agar well diffusion and broth microdilution assay, as well as time-kill test.ResultsOf the 57 Lactobacillus isolates collected, 31 had a less than 2-log reduction in their viability in both pepsin and bile salt tolerance tests. Of these 31 isolates, 5 (LUC0180, LUC0219, LYC0289, LYC0413, and LYC1031) displayed the greatest anti-CRE activity with a CRE zone of inhibition greater than 15 mm in agar well diffusion assays. The minimal inhibitory percentages of supernatants from these five strains against CREs ranged from 10 to 30%. With the exception of LUC0180, which had a minimal bactericidal percentage ≥ 40%, the bactericidal percentage of all the strains ranged from 20 to 40%. The inhibitory effect of the cell-free culture supernatants from these Lactobacillus strains did not change after heating but was abolished as the pH changed to 7.0. After a 24-h incubation, five of the Lactobacillus strains at a concentration of 108 CFU/ml totally inhibited the growth of carbapenem-resistant Escherichia coli (CRE316) and Klebsiella pneumoniae (CRE632). After a 48-h incubation, the growth of CRE316 was completely inhibited under each concentration of lactobacilli based on time-kill test. Furthermore, when the concentration of lactobacilli was at 108 CFU/ml, the decline in pH was faster than at other concentrations.ConclusionSome Lactobacillus strains exhibit anti-CRE activity, which suggests potential applications for controlling or preventing CRE colonization or infection.

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